Gaseous discharge display panel with fluorescent bodies surrounded by light attenuating material

ABSTRACT

In a display panel utilizing gas discharge, ultraviolet rays which are generated at discharge excite fluorescent bodies facing a gas discharge space and the display is effected by the luminescence of the fluorescent material in response to said rays. The fluorescent bodies are surrounded by a dielectric layer having attenuation characteristics against ultraviolet rays. These fluorescent bodies are formed in every discharge region of the plasma display panel. Thus, if the radiation of the luminous body of the display panel utilizing gas discharge diffuses in all directions, its effect does not reach the fluorescent material of adjacent fluorescent bodies and the problem of cross talk can be resolved.

United States Patent Andoh et al.

1 51 Aug. 19, 1975 [541 GASEOUS DISCHARGE DISPLAY PANEL 3,559,190 1/1971 Bitzer et al. 313/201 X WITH FLUORESCENT BODIES 1562.737 2/1971 Wiederhorn et al 313/108 A X 3,573,531 4/1971 Kerstetter et a1. 313/108 R SURROUNDED BY LIGHT MTENUATING 3,701,916 10/1972 Glaser 313/1095 x MATERIAL [75] Inventors: Shizuo Andoh; Norihiko Nakayama, Primary Examiner-Palmer C. Demeo both of Kobe, Japan Attorney, Agent, or Firm-Nels0n E. Kimmelman;

All R t P l M [73] Assignee: Fujitsu Ltd., Tokyo, Japan an a aleson [22] Filed: Mar. 22, 1973 [57] ABSTRACT [21] Appl No: 343,699 In a display panel utilizing gas discharge, ultraviolet rays which are generated at discharge excite fluores- D cent bodies facing a gas discharge space and the dis 1 1 g pp Pnoniy Data play is effected by the luminescence of the fluorescent Mar. 27, 1972 Japan 4129761 material in response to said rays The fluorescent bodies are surrounded by a dielectric layer having attenu- [521 US. Cl. .1 313/485; 313/493; 3 [3/5 1 8 ation characteristics against ultraviolet rays. These flu- [51] Int. Cl. H01] 61/42 orescent bodies are formed in every discharge region [58] Field of Search 1. 313/108 R, 109, 109.5, of the plasma display panel Thus, if the radiation of 313/188, 201. 22() 485, 493, 517. 518 the luminous body of the display panel utilizing gas discharge diffuses in all directions, its effect does not [56] References Cited reach the fluorescent material of adjacent fluorescent UNITED STATES PATENTS bodies and the problem of cross talk can be resolved, 2,933,648 4/1960 Bentley 315/169 11 Claims, 10 Drawing Figures PATENTED AUB'I 91975 SHEET 1 IF 3 Fig. PRIOR ART Fig 2 PRIOR ART T TY"? GASEOUS DISCHARGE DISPLAY PANEL WITH FLUORESCENT BODIES SURROUNDED BY LIGHT A'I'IENUATING MATERIAL The present invention relates to an improvement of a display panel utilizing gas discharge providing layers composed of fluorescent material, especially to a display panel utilizing gas discharge which decreases the cross talk which occurs when the fluorescent material is excited.

A serious cross talk problem occurs when the display of the conventional plasma display panel is colourized by using a flourescent material. In a color display tube, a fluorescent material emits light only at the point at which an electron beam is directed. Therefore, if the electron beam could be made fine and the position where the electron beam is directed could be precisely controlled, the problem of cross talk could be resolved.

However, the colorization of a display panel such as a plasma display panel is based on the idea that ultraviolet rays or infrared rays which occur at the discharge excite the fluorescent material. Therefore, the emitted light based on the discharge diffuses in all directions, and said emitted light can not be focused. That is, the emitted light which occurs in the unit discharge region is diffused from said unit region to a neighbouring unit region and affects and excites the fluorescent material of the neighbouring unit.

An object of the present invention is to provide a display panel utilizing gas discharge which overcomes the above-mentioned drawback of the conventional display panel utilizing gas discharge.

Another object of the present invention is to provide a display panel utilizing gas discharge which decreases cross talk by arranging alternately the layers composed of fluorescent material and the dielectric layers which have attenuation characteristics against an emitted light of a discharge, such as ultraviolet rays or infrared rays, exciting the fluorescent material.

A further object of the present invention is to provide a display panel utilizing gas discharge which provides alternately the layers composed of fluorescent material and the dielectric layers which have attenuation characteristics against an emitted light of a discharge, such as ultraviolet rays or infrared rays, in every gas discharge region of a display panel wherein a plurality of electrodes are arranged on two substrates which are positioned face to face with each other.

A still further object of the present invention is to provide a display panel utilizing gas discharge which provides alternately the layers composed of fluorescent material and the dielectric layers which have attenuation characteristics against an emitted light of a discharge, such as ultraviolet rays or infrared rays, exciting the fluorescent material in every discharge region of a surface discharge type display panel which provides a plurality of electrodes on one substrate and produces the discharge between adjacent electrodes arranged on the same surface.

The present invention concerns the display panel wherein there is formed a discharge space filled with gas between two inside surfaces of substrates, and which provides a group of discharge electrodes arranged at least on one of the inside surfaces of the substrates facing the discharge space, and every discharge electrodes provides a unit discharge region which can be addressed in the discharge space. The characteristic features of the present invention are that all discharge regions formed by the above-mentioned discharge electrodes are provided with layers composed of fluorescent material which are surrounded by the dielectric layers having attenuation characteristics against the emitted light generated by a discharge.

Further features and advantages of the present invention will be apparent from the ensuing description, with reference to the accompanying drawings, to which, however, the scope of the invention is in no way limited.

FIG. I is a general view of the typical gas discharge display panel known as a plasma display panel;

FIG. 2 is a sectional view of the gas discharge display panel shown in FIG. 1;

FIG. 3 is one example of a conventional display panel utilizing gas discharge which is provided with layers composed of fluorescent material;

FIG. 4A is the first embodiment of a display panel utilizing gas discharge according to the present invention;

FIG. 4B is a sectional view of the embodiment shown in FIG. 4A;

FIGS. 5, and 6 are modified embodiments of the display panel shown in FIGS. 4A and 4B;

FIG. 7 is the second embodiment of a display panel utilizing gas discharge according to the present invention;

FIGS. 8A and 8B are the third embodiment of a display panel utilizing gas discharge according to the present invention.

Referring to FIG. I, a display panel I utilizing a gaseous discharge has a pair of supporting substrates 2 and 2a. The supporting substrate 2 supports a group of electrodes 3 arranged in columns, parallel to vertical axis; dielectric layer 4 covers the group of electrodes 3. The supporting substrate 20 supports a group of electrodes 3a arranged in rows parallel to a horizontal axis; dielectric layer 4a covers the group of electrodes 3a. The supporting substrates 2 and 2a are positioned in spaced parallel relation to the groups of electrodes 3 and 3a respectively. As shown in FIG. 2 these parallel rows and columns are separated from each other by a gap 5. This gap 5 is filled with a rare gas having suitable pressure and capable of ionization. When the device 1 is utilized for display purposes, it is necessary that, at least, one of the substrates 2, 2a and one of the dielectn'c layers 4, 4a are transparent.

In the above-mentioned display panel utilizing gas discharge 1 shown in FIGS. 1 and 2, when an electric voltage higher than the firing voltage V, is selectively applied between the groups of electrodes in columns 3 and rows 30, each cross point of the electrodes in columns and rows discharges into the gap 5 filled with an ionizable gas. At the time of this discharge, a wall charge is formed on the surfaces of the dielectric layers 4 and 4a corresponding to the above-mentioned cross point. With the effect of this wall charge the discharge, which once generated is sustained with the pulsive sustaining voltage V,- smaller than the firing voltage V is continued. That is, the information which inputs as the voltage exceeding the firing voltage V; is kept in memory by the above-mentioned wall charge.

FIG. 3 shows one example of one substrate of a display panel utilizing fluorescent material in the prior art. Referring to FIG. 3, linear electrodes 4 are provided on the glass substrate 5, and these electrodes are covered with a dielectric layer 6 and fluorescent material 7. In a display panel, as shown in FIG. 1, the other substrate is arranged so that linear electrodes covered with a dielectric layer and fluorescent material 7 face the above-mentioned substrate via a discharge space. The discharge is produced in the discharge space between the dielectric layers by an electric signal which is supplied between both electrodes lines. In such a display panel utilizing gas discharge, the fluorescent material 7 having a ring form is provided on the dielectric substance in a position facing the discharge region, and is excited by ultraviolet rays generated by the discharge. However, as mentioned above, the emitted light of the discharge generated in the cross point of both electrodes is diffused in all directions and the dif fusion of this emitted light becomes the cause of cross talk.

Therefore, in the present invention, referring to FIG. 4A dielectric layers 9 and 10, and fluorescent material II, are provided in every unit discharge region determined by the discharge electrodes 12 on the glass substrate 8. FIG. 4A shows only one substrate having an arrangement of one set of electrodes and this substrate is disposed on the observing side. It is understood that the other substrate, which has other electrodes which are positioned, via a discharge space opposite the above-mentioned substrate 8, is omitted. Fluorescent materials for the other base plate may, or may not be formed. In this embodiment, material such as zincoxide or zinc-silicate can be utilized as a fluorescent material. By providing fluorescent bodies 11 as shown in FIG. 4A, the ends of the fluorescent bodies facing the discharge space can be easily penetrated by the emitted light A, which is directed at right angles to the ends of the fluorescent bodies. The emitted light which is directed obliquely is attenuated by the dielectric layer 9 and 10 and, therefore, the phenomenom of cross talk can be considerably decreased.

In the embodiment shown in FIG. 4A, the height of the fluorescent materials and the dielectric layer are the same. However, a more effective arrangement is the embodiment shown in FIG. 5, wherein the heights of the fluorescent bodies and the dielectric layer are different. As is clear from FIG. 5, an emitted light ray C which is directed obliquely, is more attenuated than the emitted light B shown in FIG. 4B. Therefore, the effect of decreasing cross talk is greater in FIG. 5 than in the embodiment shown in FIG. 4B.

In the embodiment shown in FIG. 4A, the fluorescent bodies 11 penetrate to the dielectric layer 8. However, it is not necessary that the fluorescent materials ll touch the base plate 8 as shown in FIG. 6. The embodiment shown in FIG. 6 has the advantage that fabrication can be easily carried out.

A low temperature glass which includes lead oxide (PbO) as a main component is used as a material of the dielectric layer. When a very small percentage of oxides, of impurities such as cobalt, nickel or chrome, is mixed with the above-mentioned low temperature glass, the latter becomes impervious to light. The degree of this impcrviousness to light can be controlled by the mixed amount of abovementioned impurities, and therefore, is adjustable so that ultraviolet rays are ef fectively attenuated. Helium, to which a very small amount of xenon is added, is recommended as the gas which is sealed in the discharge space.

In the above-mentioned embodiment, the attenuation layers 9 which surround each fluorescent body and attenuate the ultraviolet rays, and the dielectric layers 10, which cover each electrode, are constructed of the same material. However, it is understood that these can be constructed independently and of different materials.

Next, the second embodiment of the present invention will be explained. Beside the above-mentioned display panel utilizing vertical discharge, where two groups of electrodes are arranged respectively on two substrates, a display panel utilizing surface discharge where two groups of electrodes are arranged on only one substrate and discharge takes place between two electrodes on the same substrate is another type of display panel utilizing gas discharge. The present invention is also applicable to this type of display panel utilizing surface discharge, and the same effect is obtainable.

FIG. 7 shows the embodiment where the present invention is applied to a matrix type display panel utilizing surface discharge. Referring to F IG. 7, X electrodes 14 are provided in parallel on one substrate 13 and are covered with a dielectric layer 15. On the dielectric layer 15, Y electrodes 16 are provided parallel and at right angles to X electrodes 14. Discharge parts 17 of the X electrodes 14 are formed on the co-planar surface with the Y electrodes 16 through the dielectric layer 15 near each crossing of the X and Y electrodes. These X electrodes 14 and Y electrodes 16 are covered with a dielectric layer 18. The discharge space 20 is provided between a cover glass 19 and the dielectric layer 18. Fluorescent bodies 21 corresponding to every discharge area are provided on the inside surface of the cover glass 19 and are surrounded by the attenuation layer 22 for attenuating ultraviolet rays.

The third embodiment of the present invention will next be explained. FIGS. 8A and 8B show an embodiment where the present invention is applied to a panel utilizing surface discharge for displaying numerals. Referring to FIG. 8A, a plurality of pairs of conductive segments 24a, 25a 30a and 24b, 25b 30b, are provided on one substrate 23 to form numerals. These segment electrodes are covered with dielectric layer 31. A discharge space 32 is positioned between a cover glass 33 and the dielectric layer 31. Fluorescent bodies 34 are provided on the inside surface of the cover glass 33, and correspond in arrangement to the abovementioned segment electrodes. The fluorescent bodies 34 are surrounded by the attenuation layer 35 for attenuating ultraviolet rays.

What is claimed is:

l. A matrix type display panel utilizing surface discharge comprising,

a. a pair of dielectric substrates facing each other. at

least one of said dielectric substrates being transparent,

b. X electrodes which are provided on one of said substrates,

0. a first dielectric layer covering said electrodes,

(1. Y electrodes disposed parallel to one another and at right angles to said X electrodes on said first dielectric layer so that discharge parts of said X electrodes are formed on the co-planar surface with said Y electrodes through said first dielectric layer near each crossing portion of said X and Y electrodes,

e. a second dielectric layer which covers said X and Y electrodes so that a discharge space is formed between the other of said dielectric substrates and said second dielectric layer,

f, an ionizable gas in said discharge space,

g. means for sealing said gas within said space,

h. fluorescent bodies corresponding to every discharge part on the inside surface of said other dielectric substrate and i. a layer of ultra-violet light-attenuating material disposed completely around the sides of said fluorescent bodies but leaving exposed ends of said bodies facing said discharge space.

2. A display panel utilizing surface gas discharge comprising,

a pair of dielectric substrates disposed facing each other, one of said substrates being transparent,

a plurality of pairs of conductive segments mounted on one of said dielectric substrates, each plurality of segments being arranged so as to form a display numeral,

a dielectric layer which covers said segments which, with the other of said substrates, forms a discharge space,

an ionizable gas within said space,

means for sealing said gas within said space,

fluorescent bodies on the inside surface of said substrate and,

a layer of ultra-violet attenuating material disposed completely around the sides of said bodies but not covering the ends of said bodies facing said dis charge space.

3. A display panel utilizing gas discharge and including a pair of substrates facing each other so as to define a single continuous gas discharge space which is filled with ionizable gas, said space being sealed, at least one of said substrates being transparent, a plurality of discharge electrodes arranged on the inside surface of at least one of said substrates and facing said space forming a group of addressable unit discharge regions, said gas being freely movable throughout said discharge space, said panel being characterized by a. a plurality of fluorescent bodies respectively provided in said plurality of unit discharge regions and having portions facing said discharge space, and

b. a dielectric layer covering said electrodes and surrounding portions of said fluorescent bodies not facing said gas discharge space, the height of said dielectric layer being not less than that of said fluorescent bodies with reference to said substrate, said dielectric layer having, at least in the portions thereof surrounding said fluorescent bodies, attenuation characteristics against emitted light therefrom.

4. A display panel utilizing gas discharge according to claim 3, wherein said fluorescent bodies are supported on the inside surface of the other of said substrates.

5. The display panel according to claim 3, wherein the material of said fluorescent bodies is zinc-oxide or zinc-silicate.

6. The display panel according to claim 3 wherein the material of said dielectric layer is a low temperature glass which includes lead oxide as a main component and is mixed with a very small percentage of oxides of impurities such as cobalt, nickel or chrome.

7. A display panel utilizing gas discharge and including a pair of substrates facing each other so as to define a single continuous gas discharge space which is filled with ionizable gas, said gas being sealed within said space, at least one of said substrates being transparent, first and second pluralities of discharge electrodes arranged respectively on the inside surfaces of said pair of substrates, said first and second pluralities of discharge electrodes facing and being separated by said gas discharge space and forming a group of addressable unit discharge regions, said gas being freely movable throughout said discharge space, said panel being characterized by a. a first dielectric layer covering said first plurality of discharge electrodes,

b. a plurality of fluorescent bodies respectively provided in all of said unit discharge regions, said bodies having portions facing said first dielectric layer via said gas discharge space, and

. a second dielectric layer covering said second plurality of discharge electrodes and having portions surrounding portions of said fluorescent bodies not facing said gas discharge space, the height of said second dielectric layer being not less than that of said fluorescent bodies with reference to said substrate, said second dielectric layer having, at least in the portions thereof surrounding said portions of said fluorescent bodies, attenuation characteristics against emitted light therefrom.

8. A display panel utilizing gas discharge according to claim 7, wherein said portions of said second dielectric layer having attenuation characteristics against emitted light and the remaining portions thereof are constructed of different materials.

9. A display panel utilizing gas discharge according to claim 7, wherein said second plurality of discharge electrodes are covered with said second dielectric layer having lines projecting from said second discharge electrodes and wherein said fluorescent bodies are disposed between said projecting lines.

10. A display panel according to claim 7 wherein the material of said fluorescent bodies is zinc-oxide or zinc silicate.

11. The display panel according to claim 7 wherein said first and second dielectric layers are made of a low temperature glass which includes lead oxide as a main component mixed with a very small percentage of oxides of impurities such as cobalt, nickel or chrome. 

1. A matrix type display panel utilizing surface discharge comprising, a. a pair of dielectric substrates facing each other, at least one of said dielectric substrates being transparent, b. X electrodes which are provided on one of said substrates, c. a first dielectric layer covering said electrodes, d. Y electrodes disposed parallel to one another and at right angles to said X electrodes on said first dielectric layer so that discharge parts of said X electrodes are formed on the coplanar surface with said Y electrodes through said first dielectric layer near each crossing portion of said X and Y electrodes, e. a second dielectric layer which covers said X and Y electrodes so that a discharge space is formed between the other of said dielectric substrates and said second dielectric layer, f. an ionizable gas in said discharge space, g. means for sealing said gas within said space, h. fluorescent bodies corresponding to every discharge part on the inside surface of said other dielectric substrate and i. a layer of ultra-violet light-attenuating material disposed completely around the sides of said fluorescent bodies but leaving exposed ends of said bodies facing said discharge space.
 2. A display panel utilizing surface gas discharge comprising, a pair of dielectric substrates disposed facing each other, one of said substrates being transparent, a plurality of pairs of conductive segments mounted on one of said dielectric substrates, each plurality of segments being arranged so as to form a display numeral, a dieLectric layer which covers said segments which, with the other of said substrates, forms a discharge space, an ionizable gas within said space, means for sealing said gas within said space, fluorescent bodies on the inside surface of said substrate and, a layer of ultra-violet attenuating material disposed completely around the sides of said bodies but not covering the ends of said bodies facing said discharge space.
 3. A display panel utilizing gas discharge and including a pair of substrates facing each other so as to define a single continuous gas discharge space which is filled with ionizable gas, said space being sealed, at least one of said substrates being transparent, a plurality of discharge electrodes arranged on the inside surface of at least one of said substrates and facing said space forming a group of addressable unit discharge regions, said gas being freely movable throughout said discharge space, said panel being characterized by a. a plurality of fluorescent bodies respectively provided in said plurality of unit discharge regions and having portions facing said discharge space, and b. a dielectric layer covering said electrodes and surrounding portions of said fluorescent bodies not facing said gas discharge space, the height of said dielectric layer being not less than that of said fluorescent bodies with reference to said substrate, said dielectric layer having, at least in the portions thereof surrounding said fluorescent bodies, attenuation characteristics against emitted light therefrom.
 4. A display panel utilizing gas discharge according to claim 3, wherein said fluorescent bodies are supported on the inside surface of the other of said substrates.
 5. The display panel according to claim 3, wherein the material of said fluorescent bodies is zinc-oxide or zinc-silicate.
 6. The display panel according to claim 3 wherein the material of said dielectric layer is a low temperature glass which includes lead oxide as a main component and is mixed with a very small percentage of oxides of impurities such as cobalt, nickel or chrome.
 7. A display panel utilizing gas discharge and including a pair of substrates facing each other so as to define a single continuous gas discharge space which is filled with ionizable gas, said gas being sealed within said space, at least one of said substrates being transparent, first and second pluralities of discharge electrodes arranged respectively on the inside surfaces of said pair of substrates, said first and second pluralities of discharge electrodes facing and being separated by said gas discharge space and forming a group of addressable unit discharge regions, said gas being freely movable throughout said discharge space, said panel being characterized by a. a first dielectric layer covering said first plurality of discharge electrodes, b. a plurality of fluorescent bodies respectively provided in all of said unit discharge regions, said bodies having portions facing said first dielectric layer via said gas discharge space, and c. a second dielectric layer covering said second plurality of discharge electrodes and having portions surrounding portions of said fluorescent bodies not facing said gas discharge space, the height of said second dielectric layer being not less than that of said fluorescent bodies with reference to said substrate, said second dielectric layer having, at least in the portions thereof surrounding said portions of said fluorescent bodies, attenuation characteristics against emitted light therefrom.
 8. A display panel utilizing gas discharge according to claim 7, wherein said portions of said second dielectric layer having attenuation characteristics against emitted light and the remaining portions thereof are constructed of different materials.
 9. A display panel utilizing gas discharge according to claim 7, wherein said second plurality of discharge electrodes are covered with said second dielectric layer having lines projeCting from said second discharge electrodes and wherein said fluorescent bodies are disposed between said projecting lines.
 10. A display panel according to claim 7 wherein the material of said fluorescent bodies is zinc-oxide or zinc-silicate.
 11. The display panel according to claim 7 wherein said first and second dielectric layers are made of a low temperature glass which includes lead oxide as a main component mixed with a very small percentage of oxides of impurities such as cobalt, nickel or chrome. 